Transistor Device and Memory

This application claims a priority from the Chinese Patent Application No. 202210657949.3, filed with the Chinese Patent Office on Jun. 10, 2022, entitled “TRANSISTOR DEVICE AND MEMORY”, contents of which is incorporated herein by reference in its entirety.

The disclosure relates to the technical field of semiconductor, and in particular to a transistor device and a memory.

At present, an integrated circuit is constantly evolving to finer dimensions, with advanced process being one of the top several nodes in integrated circuit fabrication. While the size of a transistor continues to shrink, a planar transistor structure gradually shows defects such as a relatively high leakage current. Therefore, in order to meet better gate control performance and avoid the leakage current, it is a current mainstream development direction to make a three-dimensional structure of a Fin Field Effect Transistor (FinFET). However, it is difficult for the current process to further reduce a channel area on this structure, and it is difficult to further shrink the entire device structure.

Therefore, it is an urgent problem to be solved how to ensure a good gate control ability of the device and further reduce the size of the device.

In view of the above problems, the present disclosure presents a transistor device and a memory, which enhance the control ability of a gate on a semiconductor channel, and facilitate further miniaturization of the size of a device.

In a first aspect of the present disclosure, there is provided a transistor device comprising: a gate; a gate insulating layer arranged around a side of the gate; a semiconductor channel arranged around a side of the gate insulating layer away from the gate; a first source drain arranged around the side of the gate insulating layer away from the gate and located at a first end of the gate; and a second source drain arranged on the side of the gate insulating layer away from the gate and located at a second end of the gate.

In a second aspect of the present disclosure, there is provided a memory comprising the transistor device as described above.

According to one or more embodiments of the present disclosure, there is provided a transistor device and a memory, wherein in the transistor device, a gate insulating layer is arranged around a side of a gate; a semiconductor channel is arranged around a side of the gate insulating layer away from the gate; a first source drain is arranged around the side of the gate insulating layer away from the gate and is located at a first end of the gate; and a second source drain is arranged on the side of the gate insulating layer away from the gate and is located at a second end of the gate. The resulting transistor device structure forms a semiconductor channel-all-around gate, which increases the area of the semiconductor channel corresponding to the gate, effectively enhances the control capability of the gate with respect to the semiconductor channel, and facilitates further miniaturization of the size of the device. At the same time, the semiconductor channel can have a relatively large area, increasing the number of carriers and improving the performance.

The foregoing description is merely a summary of the technical solutions of the present disclosure. In order that the technical means of the present disclosure can be more clearly understood to be practiced in light of the description, and in order that the above and other objects, features and advantages of the present disclosure can be more clearly understood, the following sets forth specific embodiments of the present disclosure.

Embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood, however, that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. Furthermore, in the following descriptions, descriptions of well-known structures and techniques are omitted to avoid unnecessarily confusing the concepts of the present disclosure.

Various schematic drawings of structures according to embodiments of the present disclosure are shown in the accompanying drawings. These drawings are not to scale, in which certain details have been enlarged and may have been omitted for purposes of clarity. The shapes of the various regions and layers as well as the relative sizes and positional relationships among them shown in the drawings are only exemplary and can be deviated from in practice due to manufacturing tolerances or technical limitations, and the person skilled in the art may additionally design regions/layers with different shapes, sizes, and relative positions according to actual needs.

In the context of the present disclosure, when a layer/element is referred to as being disposed “on” another layer/element, the layer/element can be disposed directly on that other layer/element, or there can be an intervening layer/element between them. Alternatively, if a layer/element is disposed “on” another layer/element in one orientation, the layer/element can be disposed “under” the other layer/element when the orientation is reversed.

Referring to, a transistor deviceis provided in an embodiment of the present disclosure, the transistor devicecomprising a gate, a gate insulating layer, a semiconductor channel, a first source drain, and a second source drain.

In some implementations, the gate insulating layeris arranged around the side of the gate. It is understood that the gate insulating layercan be attached to the surface of the gate. That is, the surface of the gateis wrapped by the gate insulating layer. There may be other thin film layer structure between the gateand the gate insulating layer, which is not limited thereto. The semiconductor channelis arranged around the side of the gate insulating layeraway from the gate. For example, the side of the gate insulating layeraway from the gatecan be wrapped by the semiconductor channel. The first source drainis arranged around the side of the gate insulating layeraway from the gateand is disposed at a first end of the gate. The second source drainis arranged around the side of the gate insulating layeraway from the gateand is disposed at a second end of the gate.

Through the above structural design, a CAA (Channel-All-Around) structure is formed between the semiconductor channeland the gate. That is, the semiconductor channelis surrounded on the outside of the gate, which can effectively increase the area of the semiconductor channel, increase the number of carriers in the semiconductor channel, and improve the efficiency of the current conduction. At the same time, since the semiconductor channelis completely surrounded on the outside of the gate, the area of the semiconductor channelcorresponding to the gateis effectively increased, thereby improving the control ability of the gateon the semiconductor channel. This design structure increases the control area of the gateon the semiconductor channeland the area of the semiconductor channelin a limited volume and can achieve relatively small miniaturization.

In this embodiment, the contact between the semiconductor channeland the first source drainand the second source draincan be achieved in at least two ways as follows.

One optional implementation is that the first source drainand the second source drainare both arranged around the side of the gate insulating layeraway from the gate. The first source drainis connected to a first end of the semiconductor channel, and the second source drainis connected to a second end of the semiconductor channel. That is, the first source drainand the second source drainare connected at the ends of the semiconductor channel, as shown in.

Another optional implementation is that the first source draincan be arranged on the surface of the semiconductor channelaway from the gateand located at a first end of the semiconductor channel, and the second source drainis arranged on the surface of the semiconductor channelaway from the gateand located at a second end of the semiconductor channel, as shown in. This implementation can achieve a relatively large contact area between the source drain and the semiconductor channel. It is beneficial to the conduction efficiency of carriers. In addition, in the manufacturing process, the patterning mask process can be reduced, and the semiconductor channeldoes not need to be etched.

In some implementations, the second end of the semiconductor channelis wrapped by the second source drain. That is, the gate insulating layerat the second end of the semiconductor channelis wrapped by the second source drain, and the second end of the semiconductor channeland the second end of the gateextend into the second source drain, as shown in. The gateand the semiconductor channelextend into the second source drain, and the contact area between the semiconductor channeland the second source drainwill be larger.

Referring to, since the gatealso extends deeply into the second source drain, the second end of the gatecan form an electric field (referred to in this embodiment as a first electric fieldfor ease of later expression) in a direction away from the first end of the gate, and an electric field (referred to in this embodiment as a second electric fieldfor ease of later expression) can be formed in a direction to the sides of the semiconductor channel, which are the locations where the semiconductor channelis connected to the source drain. Thus, the structure of the gateand the semiconductor channelextending into the second source drainmay further enhance the control ability of the gateon the contact position of the semiconductor channelin which the semiconductor channelis in contact with the second source drain, so as to enhance the performance of the entire device and avoid the generation of a leakage current.

In some implementations, in order to ensure the control ability of the second end of the gateon the semiconductor channel, the length of the gateextending into the second source draincan be set to be not less than 10 nm, so that there is a sufficient width of the second electric fieldto ensure a better control performance on the semiconductor channelcontacted by the second source drain. At this time, the outer diameter of the end of the semiconductor channelextending into the second source draincan be controlled to be less than 50 nm to achieve device miniaturization. Of course, in some other implementations, the outer diameter of the second end of the semiconductor channelcan also be set larger, as shown in. Thus, the first electric fieldgenerated by the gateis sufficient to cover the second source drain, which can also achieve effective control of the gate. At this time, the control ability of the gateon the second end of the semiconductor channel is mainly determined by the first electric field, and the length of the gateextending into the second source drainis not limited to be less than 10 nm.

In some implementations, if a semiconductor channelwith a larger outer diameter is used, it may be difficult to reduce the size of the device. Therefore, in order to ensure that the second end of the gatehas a good control performance on the second end of the semiconductor channel, the outer diameter of the end of the semiconductor channelthat extends into the second source drainand the length of the gatethat extends into the second source draincan be controlled to satisfy a relationship: H≥0.5×(120 nm−D), where His the length of the gateextending into the second source drain, and D is the outer diameter of the end of the semiconductor channelextending into the second source drain. At this time, it is possible to control that D≤100 nm. Thus, the balance between the first electric fieldand the second electric fieldis achieved, which ensures the control performance of the gateon the second end of the semiconductor channel, and is conducive to the further miniaturization and reduction of the device, as shown in. In addition, when the semiconductor channelextends into the second source drainand does not make a penetration, both the end surface and side surface of the end of the semiconductor channelclose to the second source draincan form good contact with the second source drain, effectively reducing the contact resistance. In addition, when the diameter of the second end of the semiconductor channelis designed to be larger, the contact between the semiconductor channeland the second source draincan be further increased, reducing the contact resistance.

In some implementations, the second source drainis arranged around a surface of the semiconductor channelaway from the gateand located at a second end of the semiconductor channel. This structure can facilitate etching the second source drainto make a penetration during the manufacturing process, as shown in. Thus, the semiconductor channel, the gate insulating layer, and the gatecan be deposited within a hole, without the need for controlling the etching thickness of the second source drain.

In some implementations, the transistor devicemay further include an electrode insulating layer, which is arranged around on a surface of the semiconductor channelaway from the gateand is located between the first source drainand the second source drain. The electrode insulating layer is used to isolate the first source drainfrom the second source drain.

In some implementations, the transistor devicemay further include a substrate, which is arranged on the side of the second source drainaway from the first source drain. The gatecan be arranged perpendicular to the substrate, so that a single transistor devicewill occupy less area of the substrate, which is conducive to large-scale arrays and reduces the volume of the final product. It should be noted that “perpendicular” in this example refers to relative perpendicular or approximately perpendicular, rather than perpendicular in an absolute sense.

In some implementations, the substrate can use commonly used substrate materials, such as Si, SiO, SiC, etc., or even other flexible substrate materials, without limitation. The gatecan be made of ITO, IZO, TiN, etc., having good conductivity. It can also be made of metals or other highly conductive oxides that are favorable for growth by the ALD (Atomic Layer Deposition) process. The gate insulating layercan be implemented with materials such as HfO, HfAIO, AlO, etc. Of course, the gate insulating layercan also be made by combining multiple layers of different material films. The semiconductor channelcan be implemented with IGZO (Indium Gallium Zinc Oxide), and can also be made of derivative of IZTO (Indium Zinc Tin Oxide), IGZTO (Indium Gallium Zinc Tin Oxide) or the like with low leakage current and high mobility. The first source drainand the second source draincan be formed with TiN, W, Mo or the like, which may have better work functions for IGZO materials and better oxidation resistance properties.

Referring to, the semiconductor channelcan be implemented with IGZO material. The semiconductor channelincludes a multi-layer thin film structure. The multi-layer thin film structure includes an indium oxide thin film layer, a gallium oxide thin film layer, and a zinc oxide thin film layer. Specifically, the multi-layer thin film structure can be formed by alternately stacking the indium oxide thin film layer, the gallium oxide thin film layer, and the zinc oxide thin film layer. The order of the alternating layers is not limited. The semiconductor channelwith a high proportion of indium can reach a larger on-state current at the same gate voltage, but the threshold voltage of the device is more negative. That is, the threshold voltage of the device is less than 0 V and is more distant from 0 V. The transistor threshold voltage of the semiconductor channelwith a low proportion of indium is more positive. That is, the threshold voltage of the device is greater than 0 V, or less than 0 V but closer to 0 V, but the device on-state current will be less. It is noted that depending on the requirements for the expected performance of the device, the reference that is used to judge whether it is close to positive or negative may vary. For example, −1 V may be taken as a reference, with greater than −1 V being close to positive and less than −1 V being close to negative. Thus, the ratio of each element of indium, gallium, and zinc can be accurately controlled during fabrication by the layered structure design in this embodiment, thereby enabling adjusting and balancing of the turn-off control ability of the semiconductor channeland the mobility of the semiconductor channel.

In some implementations, the multi-layer thin film structure includes multiple unit structure layersstacked sequentially. Each unit structure layerincludes an indium oxide thin film layer, a gallium oxide thin film layer, and a zinc oxide thin film layer. With this structure, cyclic stacking of the indium oxide thin film layer, the gallium oxide thin film layer, and the zinc oxide thin film layeris achieved, which effectively improves carrier uniformity within the semiconductor channel, ensuring better mobility.

In some implementations, the unit structure layeris sequentially stacked from a direction away from the gateto a direction closer to the gateby an indium oxide thin film layer, a gallium oxide thin film layer, and a zinc oxide thin film layer. It may also be stacked by a zinc oxide thin film layer, an indium oxide thin film layer, and a gallium oxide thin film layer. It may also be stacked by a gallium oxide thin film layer, an indium oxide thin film layer, and a zinc oxide thin film layer, or by a gallium oxide thin film layer, a zinc oxide thin film layer, and an indium oxide thin film layer. Such a stacked structure may ensure that the indium oxide thin film layerand the gallium oxide thin film layerare adjacent to each other, thereby effectively suppressing formation of oxygen vacancies and improving device control ability.

In some implementations, the proportion of indium oxide material in the unit structure layeris 3/5 to 3/4, which can achieve greater on-state current at the same gate voltage condition of the transistor device. Optionally, the same ratio of the gallium oxide material as that of zinc oxide material in the unit structure layermay be provided, which guarantees better turn-off performance of the gateto the semiconductor channelwhile guaranteeing that a large on-state current is reached, achieving a balance between high current and easy turn-off of the semiconductor channel. That is, in some possible implementations, the ratio of InO:GaO:ZnOmay be ranged from 3:1:1 to 6:1:1, e.g., 5:1:1.

Further, in this embodiment, the thickness of each of the indium oxide thin film layer, the gallium oxide thin film layer, and the zinc oxide thin film layeris less than 1 Angstrom. In this way, even if the compounds of different layers are alternately deposited, the finally formed multi-element semiconductor thin film is not seen as a layered structure and can still be equivalently considered as a complete mixture of these several elements, guaranteeing the other properties of the IGZO material.

In some optional implementations, the semiconductor channelfurther includes an outer thin film layer. The outer thin film layer is disposed on the surface of the multi-layer thin film structure closest to the gate. The material of the outer thin film layer is indium oxide. That is, an additional layer of indium oxide may be deposited after the last unit structure layeris deposited, resulting in better interface characteristics and improved sub-threshold characteristics and operating current of the device. For example, if the material of the thin film of the unit structure layerclosest to the gateis ZnO, an additional layer of InOis provided on the ZnOto obtain better interface properties, as shown in.

In some implementations, the thickness of the semiconductor channelis 3 nm to 5 nm, thereby ensuring better mobility of the semiconductor channel, while also facilitating microscopic and high-density large-scale arrays of the entire transistor device.

It should also be noted that a 2T0C device structure can be conveniently formed with a small footprint since the gateof the transistor devicein this embodiment penetrates upward and the second source drainis located below, as shown in. The gateof one transistor device is connected with the second source drainof another transistor device.

In summary, according to one or more embodiments of the present disclosure, there is provided a transistor device in which the surface of a gate is wrapped by a gate insulating layer, a surface of the gate insulating layer away from the gate is wrapped by a semiconductor channel, a first source drain is arranged around the side of the gate insulating layer away from the gate and is located at a first end of the gate, and a second source drain is arranged on the side of the gate insulating layer away from the gate and is located at a second end of the gate. The resulting transistor device structure forms a semiconductor channel-all-around gate, which increases the area of the semiconductor channel corresponding to the gate, effectively enhances the control ability of the gate on the semiconductor channel, and facilitates further miniaturization of the size of the device. At the same time, the semiconductor channel can have a relatively large area, increasing the number of carriers and improving the performance.

Based on the same inventive concept, in another embodiment of the present disclosure, there is also provided a memory including a transistor device as described in any one of the preceding embodiments.

It is to be noted that the present embodiment provides a memory which employs the transistor device in the preceding embodiment, and therefore the memory has beneficial effects which can be described with reference to the preceding embodiment and will not be repeated in the present embodiment. In addition, the transistor device and the specific process implementation when each structure in the memory is fabricated may be made using existing process technology and is not limited in this embodiment.

In the above description, the technical details such as the composition and etching of each layer are not described in detail. However, a person skilled in the art should understand that layers, regions, etc. of a desired shape can be formed by various technical means. In addition, in order to form the same structure, the person skilled in the art may also devise a method which is not exactly the same as the method described above. Furthermore, although the embodiments are described separately above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

Although preferred embodiments of the present disclosure have been described, those skilled in the art may make additional changes and modifications to these embodiments once the basic inventive concepts are known. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications that fall within the scope of the present disclosure.

Obviously, those skilled in the art can make various changes and variations to the present disclosure without departing from the spirit and scope of the present disclosure. Thus, to the extent that such modifications and variations of the present disclosure fall within the scope of the present claims and their technical equivalents, the present disclosure is intended to encompass those changes and variations as well.